Segregated early weaning (SEW) is a technology that has been used on both large and small farms in recent years. Piglets are born relatively free of disease and are protected by colostrum from their dam. As piglets become older, the colostral protection begins to decrease. The piglets then become more susceptible to common organisms normally passed from sow to piglet.
In early work, SEW was used to describe the technique whereby pigs were weaned prior to days 14 to 16 of life. We commonly see pigs represented as "SEW" today that can be up to 24 days of age. The likelihood of getting "clean" piglets with older weaning is greatly diminished.
Medicated early weaning (MEW) utilizes the SEW concept along with antibiotic treatments to decrease the chance of significant transmission of organisms to the piglets. The antibiotic program is dependent on each farm's disease concerns and antibiotic sensitivity testing. This is dependent on the sow's immunity and how each organism species invades the piglet. This would include: Actinobacillus pleuropneumonia, Pasteurella multocida and Bordetella bronchiseptica.
We also know some organisms get past SEW programs. These include Haemophilus parasuis, Streptococcus suis, Porcine Reproductive and Respiratory Syndrome (PRRS), Actinobacillus suis and Proliferative enteritis (ileitis). These organisms are transferred very early in life and/or piglets do not develop good protection from the sow.
In nursery settings, the most common concerns we see are Streptococcus suis and PRRS. On many farms, an incubation time of 10 to 14 days post- weaning with Streptococcus suis is common. At that time, managers see an increase in the mortality due to septicemias (sudden deaths) and central nervous system signs (down, paddling pigs). Some units have had good results with the use of autogenous vaccines. Others have chosen strategic times for water medication (purge medication). The timing and choice of antibiotic medication depends on each farm's history and antibiotic sensitivity. Units with consistent problems medicate before anticipated outbreaks. Units with water meters may medicate on the second day of flat or declining water intakes. Individual pigs are treated with injectable antibiotics as needed.
Severity of PRRS in the nursery is related to the strain of the virus, environment, secondary organisms and management.
Disease concerns such as Actinobacillus suis and acute ileitis have become more of a problem with SEW. Both organisms can cause multiple, sudden deaths in a group overnight. On some farms, mortality rates are only slightly less with SEW because the death loss occurs in flurries. The SEW still results in less weight spread in a group and limited numbers of underweight pigs at market time.
On some grandparent farms, replacement gilts must come back to the existing "dirty" herd. This leaves the dilemma of how to acclimate gilts to get them into the herd with the least risk.
Case Study No. 1 This unit purchases weaner piglets from a 3,000-sow cooperative. Sows are weaned twice a week. Pigs are received every eight weeks in groups of 600 on Monday and 600 on Thursday. Age spread at weaning ranges from 12 to 16 days. These pigs weigh 8-10.5 lb. average. Pigs are moved into a flat deck nursery at weaning and remain there for eight weeks. The pigs are then moved all-in, all-out to double-curtain-sided, full-slat finishing facilities. The pigs are moved while maintaining pen integrity.
We were called to this unit to perform postmortems on numerous sudden deaths during the night. The pigs were in good condition and weighed approximately 200 lb. A postmortem was performed on six pigs. All pigs had similar hemorrhagic pneumonic lesions in the lungs. Culture and sensitivity yielded an Actinobacillus suis from numerous pigs. Individual pigs were injected with penicillin and the group was started on broad-spectrum antibiotics in the water, pending lab results. This group responded well. Subsequent groups have yielded only an occasional Actinobacillus suis.
Case Study No. 2 This unit receives weaned pigs from a local farrower who farrows in a group system. These pigs arrive every eight weeks in groups of 400. Average weight is about 10 lb. Average age is about 14 days. These pigs come into a converted barn with raised decks and plastic flooring. From the nursery the pigs are moved all-in, all-out to the finisher. Pigs are commingled and sorted as they go to the fully-slotted, double-curtain-sided finishing building. Pigs in this unit would often break with a Streptococcus suis type 7 septicemia around 14 days post-weaning. Multiple deaths would occur over a one-week period.
This farm elected to purge medicate because of labor concerns with injection of individual pigs. From culture and sensitivity results a water medication was administered for three days, then off for seven days, then on for three days again. This has nearly eliminated the previous Strep problem.
Laboratory workups are essential to understanding disease concerns. From there, you can work out an intervention plan that is best for your farm.